A technique of a time-series image process in which an image process of addition or subtraction is performed for plural pieces of image data obtained in different time phases and temporal changes of an imaging target are extracted has been widely used in various fields. Especially, with the advanced performance of devices in the medical image diagnostic field, attention has been paid to technical development relating to not only a technique of imaging the shape of tissue that has been the mainstream, but also a function evaluation technique of evaluating the property of tissue. In the ultrasonic diagnosis, the imaging time of an image is shorter as compared to an MRI (Magnetic Resonance Imaging) device or a CT (Computed Tomography), and temporal changes can be captured in fine temporal resolution. Therefore, a function evaluation by the time-series image process is especially effective, and many manufacturers have proposed characteristic function evaluation techniques. For example, a technique of estimating the hardness of cancer in such a manner that tissue of interest is compressed from the body surface and the distortion amount of the tissue is calculated on the basis of image data before and after the compression has be used mainly in the breast cancer diagnostic field. Further, in the contrast diagnostic field, there has been widely known a technique in which a process of selecting the maximum brightness is performed on a pixel basis for a series of image data obtained in a process in which a contrast dye flows into tissue of interest and vascular distribution is highlighted.
An important technique in such a time-series image process is a technique of correcting the positional shift of an imaging target occurring between the pieces of image data. In the medical field, an opportunity for obtaining image data is limited due to the burden on patients and the procedure of applying a contrast dye, and thus it is important how the effect of the positional shift is eliminated from the obtained image data. For example, Patent Literature 1 and Patent Literature 2 are related prior arts.
In the correction technique of Patent Literature 1, the resolution of image data to be corrected is reduced to obtain characteristic information using a Laplacian filter. Using the characteristic information, the movement between the pieces of image data is corrected. In the correction technique of Patent Literature 2, image data to be corrected is divided into plural areas, and a correction amount is measured for each area, so that body motion components including deformation of the target are evaluated.